Photo Uploader for Cloudinary compatible with react native - no jquery

CloudinaryPhotoUploader.js

import CryptoJS from 'crypto-js';
import _ from 'lodash';

// http://cloudinary.com/documentation/upload_images#creating_api_authentication_signatures
const SUCCESS = 200;

export class Cloudinary {

    constructor(apiSecret, apiKey, cloudName = 'my cloud name', createTimestamp = _.now) {
        this.apiSecret = apiSecret;
        this.apiKey = apiKey;
        this.cloudName = cloudName;
        this.createTimestamp = createTimestamp;
    }

    signQuery(payload){
        let first = true;
        let toSign = '';
        _.each(payload, (value, key) => {
            toSign += `${first?'':'&'}${key}=${value}`;
            first = false;
        });
        console.log('signature', toSign);
        return CryptoJS.SHA1(toSign + this.apiSecret).toString();
    }

    uploadImage(uri) {
        let upload_url = 'https://api.cloudinary.com/v1_1/' + this.cloudName + '/image/upload';

        let xhr = new XMLHttpRequest();
        xhr.open('POST', upload_url);
        xhr.onload = () => {
            if (xhr.status === SUCCESS && onUploadComplete) {
              console.log('photo uploaded successfuly';
            }
            else {
                console.log('something went wrong', xhr);
            }
        };
        const formdata = new FormData();
        // needs to be ordered as the Signed Query do not ensure the order for now.
        const formPayload = {
            folder: 'my_folder',
            timestamp: this.createTimestamp()
        };
        const signature = this.signQuery(formPayload);

        formdata.append('file', {uri: uri, type: 'image/png', name: 'upload.png'});
        formdata.append('api_key', this.apiKey);
        _.each(formPayload, (value, key) => {
           formdata.append(key, value);
        });
        formdata.append('signature', signature);
        xhr.send(formdata);
        return xhr;
    }

}